Orthodontic anchorage

ABSTRACT

An orthodontic tooth-crown anchorage which takes the form of an endless plastic elastomeric band that is stretchable about, and securable (as by cementing) to, such a crown. An opening is provided in the band for receiving and exposing an attachment, such as a bracket, button, cleat, hook or tube, for enabling the connecting of an external ligature device or the like. Such an attachment includes a base adapted to be clamped between a tooth crown and a band fitted thereon.

United States Patent [191 Anderson ORTHODONTIC ANCHORAGE [75] Inventor: Roland M. Anderson, Lake Oswego,

Oreg.

[73] Assignee: Modcom, Inc., Canby, Oreg.

[22] Filed: July 11, 1974 21 Appl. No.: 487,387

[52] US. Cl 32/14 A [51] Int. CI. A61C 7/00 [58] Field of Search 32/1, 14 A, 14 E; 24/3 A,

24/17 B, 73 ES, 80, DIG. 4; 248/54'R, 74 B,

[56] References Cited UNITED STATES PATENTS 2,022,557 11/1935 Caggiano 24/DIG. 4 2,705,367 4/1955 Berke 32/14 A Dec. 16, 1975 3,303,715 4/1974 Wallshein 32/14 A Primary ExanzinerLouis G. Mancene Assistant Examiner-J. Q. Lever Attorney, Agent, or Firml(o1isch, Hartwell,

Dickinson & Stuart [57] ABSTRACT An orthodontic tooth-crown anchorage which takes the form of an endless plastic elastomeric band that is stretchable about, and securable (as by cementing) to, such a crown. An opening is provided in the band for receiving and exposing an attachment, such as a bracket, button, cleat, hook or tube, for enabling the connecting of an external ligature device or the like. Such an attachment includes a base adapted to be clamped between a tooth crown and a band fitted thereon.

2 Claims, 5 Drawing Figures U.S. Patent Dec. 16, 1975 ORTHODONTIC ANCHORAGE BACKGROUND ANDSUMMARY OF TI-IE INVENTION.

This invention pertains to an orthodontic anchorage for attachment to the crown of a person s tooth. More particularly, it pertains to such an anchorage which features an endless mouth-acid-resistant elastomeric band which is stretchable about and securable to such a crown.

As is well understood, orthodontics requires that secure anchorages be provided on various teeth in a persons mouth, in order to enable the development of tooth-position-correcting and jaw-position-correcting forces within the mouth through various attachments (e.g., brackets, hooks, etc.) which form parts of these anchorages. The traditional way of producing such an anchorage has been to cement a'metallic band on a tooth, with this band having welded to the outside of it one or more of various kinds'of attachments, such as the several attachments just mentioned. Another technique which has been developed more recently involves the cementing of plastic attachments directly onto teeth, without using any bands whatsoever.

Both of these approaches, however, have drawbacks. Metallic bands are expensive, and must usually be stored in relatively large numbers and in various sizes in an expensive inventory in an orthodontists office. Further, although some effort has been 'made to precontour bands so that they will better fit particular teeth, such bands are essentially nonstretchable, and must at least be large enough throughout in order to fit completely over the contact area of the crown of a tooth, which typically is the largest part of many teeth. Hence,

despite preforming efforts, truly snugly form-fitting metallic bands have not always been achieved. Prior art attempts to provide slots in bands which enable some postfitting deformation thereof to seat around teeth have the drawback that they are weakened by such slotting, and further that they expose edges which can become irritants and food collectors in the mouth.

Yet another drawback with metallic bands is that they must be hammered and swedged ontoteeth,'which operation can be quite uncomfortable and painful.

The cementing of plastic attachments directly onto teeth, while eliminating the use of bands, has not proven entirely satisfactory. To begin with, they do not hold in place well. Further, they do not protect teeth against the accumulation of food particles, and the formation of difficult-to-remove plaque.

A general object of the present invention, therefore, is to provide a novel orthodontic anchorage which overcomes the drawbacks and difficulties encountered with prior art anchorage solutions.

More particularly, an object of the invention is to provide a very low cost, easily used, comfortably installed anchorage which has great strength when installed, and which functions efficiently to transmit positioncorrecting forces to teeth and jaws in a persons mouth.

Still another object of the invention is to provide such an anchorage with respect to which only a few sizes of parts need be stored in an orthodontists office, which feature, together with low overall cost, minimizes the expense and extent of an in-office required inventory.

According to a preferred embodiment of the invention, what is proposed is an orthodontic tooth-crown able about, and securable (as by cementing) to, such a crown. An openingisprovided in the band for receiving and'exposing an attachment such as a bracket, button, cleat, hook or tube, for the-attachment of an external ligature device or the like. Such an attachment is preferably somewhat like the plastic attachments mentioned earlier, and includes a base adapted to be clamped between a tooth crown and a band fitted thereon.

An important feature of the proposed band is that it may readily be stretched for fitment on a crown, and when relaxed closes itself around the crown, in tension, and contoured for substantially complete complementary embracement of the confronting and underlying surface of the crown. Thus, the band,.even in the absence of any cementing which maybe used between it and a tooth crown, achieves a good, secure, close-fitting grip with a crown. Only a relatively few sizes (e.g., diameters) of bands are required to handle all teeth in a persons mouthperhaps as few as three, four or five sizes. Fitting of such a band on a tooth involves practically no discomfort to a patient since no hammering or swedging is required.

Additionally, bands of the type just generally outlined can be made and sold at relatively low cost.

These and other objects and advantages which are attained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings.

DESCRIPTION OF DRAWINGS FIG. 1 is a simplified perspective view illustrating, in separated condition, a band and a cooperating-attachment as contemplated by the present invention.

FIG. 2 is a front elevation, on about the same scale as FIG. 1, illustrating the band and attachment of FIG. 1 assembled but not installed, on a tooth.

FIG. 3 is a view also on about the same scale as FIGS. 1 and 2, illustrating the assembled band and attachment of FIG. 2 stretched on the ends of a pair of spreading pliers ready for placement on a persons tooth.

FIG. 4 is a fragmentary'front elevation, on about the same scale as FIGS. l -3, showing the assembled band and attachment mounted on the crown of a persons tooth.

And, FIG. 5 isan enlargedfragmentary cross-sectional view taken generally along the line 5-5 in FIG. 4 I

DETAILED DESCRIPTION O INVENTION Turning now to the drawings, and referring first to FIG. 1, indicated generally at 10 is anchorage apparatus as contemplated herein for establishing an orthodontic anchorage with the crown of a persons tooth. Apparatus 10 includes a band 12 and an attachment l4 usable, as will be explained, with the band.

Band 12 herein takes the form of an endless unitary annulus, formed of a suitable elastomeric mouth-acidresistant plastic material, such as a commercially available thermosetthermoplastic, polyester-based, isocyanate-terminated, urethane resin. While various meth ods may be used to produce a band such as. band .12, one technique which is considered to offer advantages is to produce such a band as slice removed froman elongated tube of the appropriate material. For the purpose of illustration herein, the top and bottom of the band are shown as being substantially planar, and as lying in spaced parallel planes, as if straight-sliced from such a tube. However, with respect to use of such a band with certain teeth in a persons mouth, it may be desirable to curve the bottom edge of the band (rather than have it planar) so that it will conform to the gum line around the tooth.

Suitably formed in the wall 12a of band 12, at a single location therein in the band illustrated, is a generally circular opening 12b.

Band 12 herein, for example, is sized for fitment on the crown of one of the larger teeth in a persons mouth, such as a bicuspid, and according to the invention, has a relaxed-state inside diameter which will require stretching of the band in order to place it about the crown of such a tooth. A typical inside diameter for such a band might be about 5/ 16-inches.

Attachment 14 herein includes what might be thought of as a substantially flat base 14a from the front side of which projects, centrally, a connecting portion 14b which, in the particular attachment illustrated, takes the form of a conventional lingual button. It should be understood that the projecting connecting portion in an attachment may take the forms of other conventional orthodontic connecting devices, such as a bracket, a hook, a tube, etc. Preferably, attachment 14 is formed of a suitable mouth-acid-resistant rigid plastic material, such as a suitable polycarbonate plastic material.

As contemplated herein, opening 12b in band 12 is sized to permit free insertion therethrough, from the inside to the outside of the band, of a projection in an attachment, such as button 14b. Base 14a, however, has a sufficiently large extent that it will not itself pass through the nominal size of opening 12b.

Referring particularly to FIG. 2 which illustrates the band and attachment assembled, here, button 14b projects forwardly through opening 12b so that it is ex posed on the outside of band 12, and base 14a is disposed against the inside of wall 12a around opening 12b. This assembled condition of the band and attachment is the condition in which apparatus is placed just prior to its being fitted on the crown of the tooth.

Turning now to FIGS. 3, 4 and 5, in FIG. 3, there are shown at 16, 18 the ends of a pair of spreading pliers, which ends have curved outside surfaces, with these ends inserted in band 12, and spread somewhat to stretch the band. Preferably, each of the plierss ends has a width somewhat greater than the tooth with respect to which band 12 is to be fitted so that when the band is stretched as shown in FIG. 3 there is a central opening 20 through the band which is larger than the largest part of the crown of the tooth.

With the band thus stretched, it is maneuvered in any suitable fashion over the selected too, such as the bicuspid shown fragmentarily at 22 in FIGS. 4 and 5. In FIGS. 4 and 5, apparatus 10 is shown in a finally placed or fitted condition on the crown of tooth 22. It should be mentioned that prior to placement of the band and attachment on the tooth, the inside face of wall 12a as well as the inside face of attachment base 14a are preferably coated with a suitable cement or bonding agency to assure firm adhesion with the outside surface of the tooth crown. A cement which has been found to work satisfactorily is an acrylic cement, such as methyl methacrylate. Such a cement produces what might be referred to as a physical as distinguished from a chemical bond between the plastic parts in apparatus 10 and tooth 12. Were it desired to have a cement adhere even more firmly to the plastic parts, a suitable cement which produces a chemical bond with these parts may be selected and used if desired. Further, and in certain applications, it may be desirable to prepare specially that location on the crown which will underlie base 14a in attachment 14, so as to assure an especially tight grip between the attachment and the crown. This might be accomplished through conventional tooth-etching techniques which expose minute openings in the enamel of the tooth wherein a good mechanical bond can be achieved with a cement.

With the apparatus installed as shown in FIGS. 4 and 5, band 12 is in tension around the crown of the tooth 22, and clamps base 14a between wall 12a and the outside of the crown. It is especially noticeable in FIG. 4 that band 12, through internal tension, has contoured itself into substantially complete complementary embracement of the underlying confronting surface of the crown. Thus, the apparatus fits snugly on the crown in very compact form. As can be seen clearly in FIG. 5, button 14b is exposed on the outside of the band for ready attachment of an orthodontic ligature device or the like.

It will be noted that band 12 has been described as containing but a single opening 12b. In certain applications, it may be desirable to use a band having two or more such openings to accommodate a plurality of attachments at different locations around the band. This, of course, is entirely possible, and is contemplated as an expected and useful modification of the preferred embodiment of the invention.

With the apparatus of the invention, the various features and advantages ascribed to it earlier are obviously readily attained. Only a few sizes of bands need be provided for handling the range of tooth sizes found in the ordinary mouth. Stretchability in the bands enables their simple placement over teeth, with subsequent tight self-conforming to the outside shapes of teeth. Time-consuming welding techniques which have been required in the past with metallic bands in order to join attachments are obviated by a structure permitting the ready insertion through the opening or openings in a band of selected separate attachments. Little discomfort, if any, is associated with mounting and fitting of a band and attachment.

While a preferred embodiment, and certain modifications, of the invention have been described herein, it is appreciated that other variations and modifications may be made without departing from the spirit of the invention.

It is claimed and desired to secure by Letters Patent:

1. Orthodontic anchorage apparatus adapted for mounting on the crown of a tooth comprising an endless, mouth-acid-resistant, elastomeric band elastically stretchable over and removably securable to such a crown for tight fitment thereon, said band when so fitted being in tension and contouring itself for substantially complete complementary embracement of the confronting surface of the crown,

means defining an opening in said band, and

an orthodontic attachment enabling the connection thereto of external orthodontic equipment, said attachment including a connecting portion insertable through said opening from the inside to the outside of said band so that the connecting portion when so inserted is accessible from the outside of the band, and a generally flattened base portion joined to said connecting portion and sized to prevent its own passage through said opening, said base portion being constructed whereby, with said connecting portion inserted through said opening, and said band fitted on a crown, the base portion is clamped in place between the band and the crown.

2. Orthodontic anchorage apparatus in operative condition on the crown of a persons tooth comprising an endless, mouth-acid-resistant, elastomeric band elastically stretched about and secured to said crown, said band being tensed about the crown,

and crown. 

1. Orthodontic anchorage apparatus adapted for mounting on the crown of a tooth comprising an endless, mouth-acid-resistant, elastomeric band elastically stretchable over and removably securable to such a crown for tight fitment thereon, said band when so fitted being in tension and contouring itself for substantially complete complementary embracement of the confronting surface of the crown, means defining an opening in said band, and an orthodontic attachment enabling the connection thereto of external orthodontic equipment, said attachment including a connecting portion insertable through said opening from the inside to the outside of said band so that the connecting portion when so inserted is accessible from the outside of the band, and a generally flattened base portion joined to said connecting portion and sized to prevent its own passage through said opening, said base portion being constructed whereby, with said connecting portion inserted through said opening, and said band fitted on a crown, the base portion is clamped in place between the band and the crown.
 2. Orthodontic anchorage apparatus in operative condition on the crown of a person''s tooth comprising an endless, mouth-acid-resistant, elastomeric band elastically stretched about and secured to said crown, said band being tensed about the crown, and through said tension selfcontoured into substantially complete complementary embracement of the confronting surface of the crown, an opening in said band along a side of said crown, and an orthodontic attachment enabling the connection thereto of external orthodontic equipment, said attachment including a connecting portion extending through said opening and exposed on the outside of said band, and a base portion joined to said connecting portion and clamped between said band and crown. 